Magnetohydrodynamics

Description: This is an electrical propulsion method without moving parts, applicable to any conductive fluid, including water, liquid metal, or plasma. The principle is demonstrated using water. Essentially, two electrodes in water have a current passed between them in a magnetic field, forcing the water out the back and creating thrust. While it is not a commercially viable proposition, it was featured in "The Hunt for Red October" as the Soviet stealth submarine. In this model, there are two 1-inch NIB magnets positioned about an inch apart. At right angles to these magnets are two electrodes that pass approximately 1.6 A at 9.6 VDC in salt water, totaling around 15 watts. The power source is a model car NiCd battery pack. The entire construction, which is not seaworthy, is made of balsa wood and measures about 8 inches in length. When using off-board power of 1 kW (100 V, 10 A), there is significantly more activity, producing hydrogen and oxygen or chlorine bubbles streaming from the stern. However, a larger tub of saltwater is needed for speed testing. The ignition of the hydrogen bubbles produces a bright yellow flame from the sodium in the seawater, which is normally almost colorless. Over time, the electrodes wear away, causing the water to fill with debris, likely insoluble salts from the metal electrodes.

Features include 2.5 times the power (16 alkaline AA cells providing 24 V compared to the previous 9.6 V NiCd pack) and typically 50 W output from a saltwater swimming pool (20 V, 2.5 A) to a near-saturated salt solution (12 V, 4.5 A). A description of the Japanese MHD boat, the "Yamoto," manufactured by Mitsubishi in the 1990s and weighing 185 tons, indicates it traveled at 15 km/h. It utilizes a superconducting 4 Tesla magnet, and the round cross-section of the motor resembles this model but is approximately ten times larger in diameter (260 mm). The electrodes are made of titanium, with the anode coated in DSA and the cathode plated with platinum. The length of the electrodes is 3.4 m.

A fascinating article with numerous diagrams discusses an array of Hall effect sensors used to drive LEDs for visual indication of a magnetic field and its direction. This system contains 44 UGN3503 Hall effect devices, which output 2.5 V in the absence of a magnetic field. When a south pole is presented, the voltage increases by 1.3 mV/gauss, and a similar response occurs in the reverse direction (10,000 gauss = 1 Tesla). The devices operate on 5 V, and the 44-device array draws 500 mA. The left photo shows no magnetic field, with only the red LEDs illuminated. The center photo demonstrates the green LEDs lighting up with the applied south pole field from a NIB magnet, while all LEDs turn off with an applied north pole field. The right photo captures the field from a microwave oven transformer (MOT) with DC current passing through it. There is capacity for 88 Hall effect devices if expansion is desired. The array provides real-time responses with a frequency response of 23 kHz, suitable for applications such as a can crusher. It reacts to minimal movements with intensity or color changes, exhibiting a dynamic response beyond what still photos can convey.

The circuit utilizes the output from the Hall effect devices to source current sufficient to drive the red and green LEDs, which connect to ground through their respective 510-ohm resistors. The differing responses are due to varying voltage drops, with red LEDs typically around 2 volts and green LEDs around 3 volts. The left photo captures the array in motion, taken with a time exposure of 4 seconds, while positioned over three magnets. The center photo illustrates a similar setup demonstrating the field of a loudspeaker magnet removed from its cone and support. The right photo showcases a more complex multi-sectored magnet from a video motor, highlighting the misalignment of the fields as indicated by the red and green LEDs.This is an electrical propulsion method with no moving parts which applies to any conductive fluid including water, liquid metal or plasma. Here I am demonstrating the principle with water. Essentially two electrodes in water have a current passed between them in a magnetic field and the water is forced out the back creating thrust.

It is not real ly a commercial proposition but was featured in "The Hunt for Red October" as the Soviet stealth sub. In my model there are two 1 inch NIB magnets about an inch apart. At right angles to this are two electrodes which pass about 1. 6 A 9. 6 VDC in salt water. ie about 15 watts. Power is by a model car NiCd pack. The whole decidedly unseaworthy construction is made of Balsa and is about 8 inches long. Using off board power of 1kW (100V 10A) there is a lot more action and production of hydrogen and oxygen or chlorine bubbles streaming from the stern, but I don`t have a big enough tub of saltwater to test it for speed.

On the right is the ignition of the hydrogen bubbles with the bright yellow flame from the sodium in the seawater bubbles. Normally a hydrogen flame is almost colourless. After a short while the electrodes wear away and the water fills with debris, presumably insoluble salts of the metal electrodes.

Features: 2. 5 times the power (16 alkaline AA cells giving 24V - previously 9. 6V NiCd pack) Typically 50W output from salt water swimming pool (20V 2. 5A) through to near saturated salt solution (12V 4. 5A. I have finally found the description of the Japanese MHD boat, the "Yamoto" made by Mitsubishi in the 1990`s and weighing 185 tons which travelled at 15 km/h. It uses a superconducting 4 Tesla magnet, and the round cross section of the motor looks remarkably like mine but about 10 times the diameter (260mm).

Electrodes are Titanium with anode coating of DSA ( ) and the cathode plated with Platinum. The length of electrodes is 3. 4 m. Fascinating article with lots of diagrams. This uses an array of Hall effect sensors to drive some LED`s to give a visual indication of a magnetic field and its direction. It contains 44 UGN3503 Hall effect devices. They output 2. 5 V in no field. Present a south pole and voltage goes up by by 1. 3 mV/gauss and the same in the reverse. (10, 000 gauss = 1 Tesla). They run on 5 V and the 44 device array shown here draws 500 mA. Above, left photo shows no magnetic field. The red LED`s are on only. The center photo shows the green LED`s light up with the applied south pole field from a NIB magnet and all turn off with an applied north pole field.

The right photo shows the field from a MOT with a DC current passing through it. There is room on board for 88 Hall effect devices if I wish to expand. Note that this array gives a real time response with a frequency response of 23 kHz which is in the range of my can crusher. It responds to the slightest movement with intensity or colour changes and is a lot more dynamic than the still photos would indicate.

Think of a colour Magnadoodle R. The circuit uses the output which sources current at a sufficient level to drive the red and green LED`s which connect to ground with their respective 510 ohm resistors. The differing response is due to the different voltage drops with red LED`s being in the 2 volt range and green LED`s in the 3 volt range.

Above, left photo shows the array moving by hand in a time exposure shot of 4 seconds with magnets below the plastic sheet. It has many passes over 3 magnets. There are two south poles of two ferrite rings and a stronger NIB magnet adjacent showing a (black ) "hole" where the NIB has been turned north up.

Hand is faster than the eye here. The center photo shows a similar setup but demonstrating the field of a loudspeaker magnet removed from the cone and support. The right photo shows a more complex multi sectored magnet out of a video motor. Note that the fields do not line up properly as the red and gre